package com.itheima.chapter08.list.Generic.four;

import java.util.ArrayList;
import java.util.List;

public class demo {
    public static void main(String[] args) {
        List<?> list1 =new ArrayList<Object>();
        List<?> list2 =new ArrayList<Number>();
        List<?> list3 =new ArrayList<Integer>();
        System.out.println("===================");
        //extends:本身或其子类
       // List<? extends Number> l1 =new ArrayList<Object>();
        List<? extends Number> l2 =new ArrayList<Number>();
        List<? extends Number> l3 =new ArrayList<Integer>();
        System.out.println("===================");
        //super:本身或其父类
        List<? super Number> s1 =new ArrayList<Object>();
        List<? super Number> s2 =new ArrayList<Number>();
        //List<? super Number> s3 =new ArrayList<Integer>();
    }
}
